1. Field of the Invention
The present invention relates to a gasborne component condensing apparatus, for example, for use in condensing processes of various kinds of solvent vapor contained in exhaust air or gas generated from a painting facility, electronic-component manufacturing facility and so on.
The invention relates more particularly to a gasborne component condensing apparatus for condensing condensation-target component contained in treatment-object or object gas (i.e. gas to be treated) by effecting an adsorbing step for adsorbing the condensation-target component in the object gas to an adsorbent layer by causing the gas to pass the layer and a desorbing step for desorbing the condensation-target component adsorbed to the adsorbent layer at the adsorbing step into desorbing gas by causing the desorbing gas smaller in the amount and higher in the temperature than the object gas to pass the adsorbent layer after the adsorbing step, the apparatus effecting the adsorbing step and the desorbing step for a plurality of cycles, so that the desorbing gas delivered from the adsorbent layer and containing the condensation-target component desorbed during the desorbing step is collected as a condensed gas product.
2. Description of the Related Art
According to a conventional gasborne component condensing apparatus of the above-noted type, the entire amount of the desorbing gas caused to pass the adsorbent layer during the desorbing step (i.e. the entire amount of the desorbing gas delivered from the adsorbent layer and containing the condensation-target component desorbed from the adsorbent layer) is collected as a condensed gas product.
However, comparing an earlier stage of the desorbing step with a later stage of the same, the temperature of the adsorbent layer is still low at the earlier stage, so that much of the heat retained in the high-temperature desorbing gas caused to pass the adsorbent layer is used up for heating the adsorbent layer, so that there occurs a significant temperature drop which impairs the efficiency of the desorption of the condensation-target component adsorbed to the adsorbent layer. For this reason, at the such earlier stage of the desorbing step, the desorbing gas delivered from the adsorbent layer is lower in the concentration of the condensation-target component. Because of the above, according to the conventional apparatus, it was not possible to increase sufficiently the average concentration of the condensation-target component in the delivered desorbing gas (i.e. condensed gas product) through the entire step from the earlier stage to the later stage thereof, so that the concentration rate available from the apparatus would be limited disadvantageously.
Further, in case the condensed gas product obtained from this gasborne component condensing apparatus is subjected to an aftertreatment, an aftertreating facility of a greater treating capacity will be needed due to the limited concentration rate available from the condensing process as the xe2x80x9cpretreatmentxe2x80x9d, so that the cost of the facility itself and its running cost will be high and also a greater space will be needed for the installment of such large facility. Moreover, if the aftertreatment comprises a combustion treatment for combusting the condensation-target component contained in the condensed gas product, the insufficient concentration of the component such as solvent vapor leads to the need of a greater amount of combustion aiding fuel for the combusting process.
In view of the above-described state of the art, a primary object of the present invention is to provide a gasborne component condensing apparatus with improved construction which achieves a higher concentration rate without inviting physical enlargement of the apparatus or reduction in its processing capacity.
For accomplishing the above-noted object, a gasborne component condensing apparatus of the present invention, comprises gas sorting means for sorting the desorbing gas delivered from the adsorbent layer during said desorbing step between an earlier passage gas which passed the adsorbent layer at an earlier stage of the desorbing step and a later passage gas which passed the adsorbent layer at a later stage of the desorbing step and for subsequently causing said earlier passage gas, as a portion of the object gas, to pass the adsorbent layer again at a subsequent adsorbing step while allowing said later passage gas to be collected directly as the condensed gas product.
With the above-described construction, the desorbing gas delivered from the adsorbent layer during the desorbing step is sorted between the earlier passage gas which passed the adsorbent layer at an earlier stage of the step when the temperature of the adsorbent layer is still low and the efficiency of the desorption of the condensation-target component therefrom is also correspondingly low (that is, the desorbing gas which is delivered from the adsorbent layer with a low temperature, hence, with a low concentration of the target component) and the later passage gas which passed the adsorbent layer at a later stage of the step when the adsorbent layer has been heated to a sufficiently high temperature and the efficiency of the desorption of the target component therefrom is also correspondingly high (that is, the desorbing gas which is delivered from the adsorbent layer with a high temperature, hence, with a high concentration of the target component).
Then, the earlier passage gas, because of its low target-component concentration, is caused to pass, as a portion of the treatment-object gas, again the adsorbent layer, so that the condensation-target component contained therein is adsorbed to the adsorbent layer and then this adsorbed component is desorbed in the subsequent desorbing step into the small amount and higher temperature desorbing gas. On the other hand, the later passage gas delivered from the adsorbent layer with a high target-component concentration is directly collected as the condensed gas product.
Incidentally, with appropriate setting of the xe2x80x9csorting point or timingxe2x80x9d where the earlier passage gas and the later passage gas are sorted from each other, both the concentration and temperature of the target component in the earlier passage gas may be rendered rather low. Further, as the desorbing gas is smaller in its amount and the earlier passage gas is even smaller in its amount, the addition of this earlier passage gas to the desorbing gas as an additional portion thereof, when caused to pass the adsorbent layer in the adsorbing step, will not cause any significant increase in the processing load or in the temperature in the adsorbing process, so that resultant reduction in the adsorbing capacity may be minimal. Hence, with utilization of the above-described two methods, the originally intended performance of adsorbing and collecting the condensation-target component contained in the object gas may be maintained satisfactorily.
Therefore, according to the present invention, the earlier passage gas delivered from the adsorbent layer with a lower target component concentration is subjected again to the condensing process, whereas the later passage gas delivered from the adsorbent layer with a higher target component concentration is collected directly as the condensed gas product. Then, in comparison with the conventional apparatus which directly obtains the entire amount of the desorbing gas passed through the adsorbent layer in the desorbing step as the condensed gas product, the concentration rate of the condensing process may be effectively increased, without inviting physical enlargement of the apparatus such as increase of weight and/or thickness of the adsorbent layer or any substantial reduction in the processing capacity.
Further, in case the condensed gas product obtained from the condensing apparatus is subjected to an aftertreatment, no significant additional treating capacity will be required of the aftertreatment facility since the concentration rate has already been increased to a sufficient degree in the condensing process as the pretreatment. Consequently, the cost of such aftertreatment facility per se as well as its running cost may be significantly reduced and the space required for installment of this facility too may be significantly reduced.
For example, if the above-described construction of the present invention is utilized in the conventional apparatus which is originally adapted for obtaining directly the entire amount of the desorbing gas passed through the adsorbent layer in the desorbing step as the condensed gas product, the concentration rate may be readily doubled, without making any change in the existing adsorbent layer and without any substantive reduction in the processing capacity of the apparatus. That is to say, if the conventional condensing apparatus originally provides a concentration rate on the order of 20 times, this apparatus, if added with the feature of the present invention, will be able to provide a concentration rate on the order of 40 times.
In causing the earlier passage gas as an additional portion of the object gas to pass again the adsorbent layer in the subsequent adsorbing step, it is conceivable to mix this earlier passage gas into xe2x80x9cnewxe2x80x9d object gas which is caused to pass the adsorbent layer for the first time at the adsorbing step. Alternatively, the timing of passing the adsorbent layer and/or the passing portion within the adsorbent layer may be rendered different from each other between such new object gas and the earlier passage gas.
For accomplishing the above-noted object, according to the present invention, the above-described apparatus further comprises: a rotatable adsorbing rotor for supporting the adsorbent layer, the adsorbent layer extending in a rotational direction of the adsorbing rotor, the apparatus including, in juxtaposition along a rotational path of said rotor thereof, an adsorbing area where said object gas is caused to pass the adsorbent layer at a portion of the adsorbing rotor which portion is passing a predetermined area and a desorbing area where said desorbing gas is caused to pass the adsorbent layer at a portion of the adsorbing rotor which portion is passing a further predetermined area; and
wherein said gas sorting means includes;
a partitioning member for partitioning an outlet for the desorbing gas at the desorbing area into an upstream outlet portion located upstream in the rotational direction of the rotor and a downstream outlet portion located downstream in the rotational direction of the rotor,
a return passage for guiding the desorbing gas delivered from the upstream outlet portion to an inlet for the object gas at the adsorbing area, and
a takeoff passage for taking off the desorbing gas delivered from the downstream outlet portion as a condensed gas product.
According to the above-described construction, the period when the adsorbent layer at each portion of the rotor passes the adsorbing area in the rotational path of the rotor provides the adsorbing step for adsorbing the concentration-target component from the object gas, whereas the further period when the adsorbent layer of the rotor passes the desorbing area in the rotational path of the rotor provides the desorbing step for desorbing the adsorbed target component into the desorbing gas. Therefore, as the adsorbing rotor is revolved, the adsorption at the adsorbing area and the desorption at the desorbing area are effected alternately. As a result, the step at the adsorbing area for adsorbing and collecting the condensation-target component from the object gas (i.e. the xe2x80x9cformer stepxe2x80x9d in the condensing process) and the further step at the desorbing area for desorbing the adsorbed component into the small amount of desorbing gas (i.e. the xe2x80x9catter stepxe2x80x9d in the condensing process) may be carried out in continuous and parallel, namely, very efficient manner.
Further, as the partitioning member partitions the desorbing gas outlet at the desorbing area into the upstream outlet portion located upstream in the rotational direction of the rotor and the downstream outlet portion located downstream in the rotational direction of the rotor, the desorbing gas delivered through this outlet may be sorted between the earlier passage gas delivered from the upstream outlet portion which passed the adsorbent layer at an earlier stage of the desorbing process (i.e. the desorbing gas which passed the adsorbent layer at a rotor portion which had entered the desorbing area immediately before) and the later passage gas which passed the adsorbent layer at a later stage of the desorbing process (i.e. the desorbing gas which passed the adsorbent layer at a rotor portion which had entered the desorbing area relatively long before).
And, the desorbing gas delivered from the upstream outlet portion (i.e. the earlier passage gas delivered with a relatively low target-component concentration and low temperature) is then guided via the return passage to the object gas inlet at the adsorbing area, so that this gas, as an additional portion of the object gas, is caused to pass again the adsorbent layer at a portion of the adsorbing rotor which is now passing the predetermined area of the adsorbing area, so that this earlier passage gas may be subjected to another condensing step. Whereas, the desorbing gas delivered from the downstream outlet portion (i.e. the later passage gas delivered with a relatively high target-component concentration and high temperature) may be directly taken off from the apparatus as the condensed gas product through the takeoff passage.
That is, according to the invention described above, the former step of adsorbing and collecting the condensation-target component from the object gas and the latter step of desorbing the adsorbed target component into the desorbing gas are effected in continuous and parallel manner, so that the feeding operation of the object gas and the feeding operation of the desorbing gas may be carried out continuously. As a result, this adsorption/desorption condensing process may be effected as a continuous process of high efficiency.
And, by sorting the desorbing gas delivered from the desorbing area between the earlier passage gas to be subjected again to the condensing process as an additional portion of the object gas and the later passage gas which is to be collected directly as the condensed gas product by means of the sorting means including the partitioning member, the return passage and the takeoff passage, the effect of the invention, i.e. the possibility of high concentration rate, may be constantly achieved in such continuous condensing process.
Incidentally, according to the above construction, the desorbing gas delivered as the earlier passage gas from the upstream outlet portion is guided via the return passage to the object gas inlet of the desorbing area, so that this gas is caused to pass, as an additional portion of the new object gas, the adsorbent layer portion of the rotor at the adsorbing area. In doing this, it is conceivable to mix this earlier passage desorbing gas delivered from the upstream outlet portion with the new object gas to be caused to pass together the same adsorbent layer portion of the rotor at the adsorbing area. Alternatively, it is also conceivable to cause this desorbing gas from the upstream outlet portion and the new object gas to pass different portions of the adsorbent layer at the adsorbing area.
Further and other objects, features and advantages of this invention will become apparent from the following detailed description of the preferred embodiments thereof with reference to the accompanying drawings.